made some tests with the the VCV Rack and Numerology4 using the Bridge AU plugin and a IAC Bus for sending MIDI and it works perfect. You just have to take care that you have to save the VCV Rack beside the Numerology project.
What needs more testing is how the latency behaves if you use the VCV and other stacks side by side.
The only problem I found is that the VCV Rack in the moment only allows one MIDI in module, but they are working on a fix.